LED Illumination Compensation Using Periodic Measurement Offsets
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
LED illumination devices face challenges in maintaining consistent luminous flux due to variations in temperature and aging, which existing compensation methods struggle to address effectively, especially when interference from nearby lamps causes errors in measurement.
Innovation Solution
The method involves operating multiple emitter modules with LED elements at varying drive currents, using measurement intervals with offsets from a timing reference to distinguish between illumination and non-illumination periods, and employing photocurrent monitoring and subtraction to correct for ambient interference, ensuring accurate compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If compensation measurements are performed continuously to maintain consistent luminous flux, then luminous flux stability is improved, but measurement errors from nearby lamp interference increase
Solution Approach 1:
The system performs compensation measurements at specific periodic intervals rather than continuously, using a timing reference to schedule measurement windows. This periodic approach allows the system to maintain luminous flux consistency while avoiding continuous exposure to interference from nearby lamps, thereby resolving the contradiction between measurement frequency and measurement accuracy.
Solution Approach 2:
The system performs detection during intervals before compensation measurements to identify potential interference from nearby lamps. By detecting interference conditions in advance, the system can adjust or skip compensation measurements when interference is anticipated, preventing measurement errors while still maintaining overall luminous flux stability.
2Illumination intensity
If drive current is increased to compensate for LED aging and temperature effects, then luminous flux output is maintained, but LED lifetime and reliability deteriorate
Solution Approach 1:
The system uses photocurrent detection to continuously monitor the actual luminous flux output and provides feedback to the control circuit. Based on this feedback, the control circuit adjusts drive currents dynamically to maintain consistent luminous flux while accounting for LED aging and temperature effects, optimizing the balance between maintaining illumination intensity and preserving LED reliability.
Solution Approach 2:
The system changes operating parameters (drive currents) dynamically based on detected LED performance degradation from aging and temperature. By adjusting drive currents in response to measured changes in luminous flux, the system maintains consistent illumination output while applying minimal necessary current increases, thereby extending LED lifetime.
3Illumination intensity
If multiple emitter modules operate simultaneously to provide sufficient illumination, then lighting output is improved, but interference between modules during measurement increases
Solution Approach 1:
The system segments the operation of multiple emitter modules by controlling them to operate in alternating intervals rather than simultaneously during measurements. Each module is measured separately while others are turned off or operated at reduced current, eliminating mutual interference while maintaining overall lighting output through coordinated operation.
Solution Approach 2:
The system uses periodic measurement intervals with timing offsets for different emitter modules, allowing each module to be measured during dedicated time windows when other modules are not interfering. This periodic segmentation of measurement and operation maintains sufficient overall illumination while eliminating interference during critical measurement periods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for precise adjustment of drive currents to maintain consistent luminous flux, reducing errors caused by temperature and aging changes while minimizing interference from nearby lamps, thereby enhancing the reliability and accuracy of LED illumination devices.
Implementation Method 1
multiple emitter modules, each including multiple emission light emitting diode (LED) elements
Implementation Method 2
operating one or more of the multiple emission LED elements in each of the multiple emitter modules at a respective substantially continuous drive current sufficient to produce illumination
Implementation Method 3
monitor a measurement photocurrent induced in a measurement photodetector within the emitter module
Data Source
AI summary
A method and light emitting diode (LED) illumination device comprising multiple emitter modules are provided. In one embodiment, the method includes bringing to a level insufficient to produce illumination the respective drive currents of all except one of multiple emission LED elements within respective first and second emitter modules for the duration of a measurement interval within respective first and second series of measurement intervals. The measurement intervals are interspersed with periods of illumination, and the first and second series of measurement intervals are separated by respective first and second offsets from a timing reference. An embodiment of an illumination device includes multiple emitter modules, where each emitter module includes multiple emission LED elements and one or more photodetectors. The illumination device further includes a lamp control circuit adapted to perform steps of the method.